One of the biggest problems facing the car wash industry is the disposal or recycling of grit trap waste or pit sludge. Car wash waste water is often collected in a pit. The water carries with it considerable solid waste or sediment that is washed off the cars. The dispersion of solids, many of which are toxic, cannot be deposited with the water directly into sewers. The bulk of the solid waste settles in the bottom of the pit. The solid waste in the bottom of the pit is still too wet for disposal. Car wash operators are then faced with the task of dewatering the solids, i.e., separating the solids from the water, and disposing of the solids. The crudest method is to shovel the solids from the bottom of the pit, deposit the solids on the ground in the open air and allow the water to evaporate. This requires considerable manual labor and time.
Various vacuum devices have been devised that can loosen the particulate materials from the bottom of a depressed enclosure or pit with a stream of water under pressure and vacuum the mixture up out of the pit. U.S. Pat. No. 4,943,211 discloses a device to remove filter sand from swimming pool filtering systems. However, sludge extracted in that manner from car wash pits would be accompanied with a considerable amount of water. Landfills will not accept such wet sludge since toxins present in the solid waste will leach out into the soil. Toxins of greatest concern are lead, benzene and other petroleum carbons.
The present invention provides a simple and inexpensive way to separate the solids in dry enough condition so that they will meet landfill, local and Environmental Protection Agency requirements for disposal. Although the present invention is especially useful for the car wash industry, it is also useful for any situation where liquids containing solid particulates are present in an enclosure and separation is desirable. Certainly other vehicle washing facilities are faced with the same problem as car wash establishments, i.e., contamination with hazardous substances or petroleum products. Storm sewer traps, flooded basements, swimming pools, wash racks in tool rental agencies, sediment filled boat slips, traps for wash water used in washing materials in manufacturing operations, gold filled river beds and septic tanks can also benefit by employing the product and process of the present invention to separate particulate materials especially solids from liquids. "Pit" or "trap" as used herein refers to any natural or man-made enclosure containing particulate materials which can be retrieved by admixture with liquids and thence separated therefrom.